Massey Ferguson 165 gas with a Zeinth carb::: Problem I can t get figured out. It died while mowing hay, got it to run but no more than 1/2 throttle. No biggie figured fuel line was dirty. Ran like that for awhile then completely died. Replaced points, plugs, cap and Rotor. Still no success. Disassembled to open valve cover, distributor was out of time. Put it back together no real luck. Retimed again got it to run. But not right. Acted to not be getting fuel. The fuel shut off Selinoind in the carb was not working at all when bench tested with 12 volts. Unable to find one I cut the tip off and put it back together now the tractor was running farrely well. Put gas tank and tin work back on, now nothing again. My dad tinkered with it and now it pyshically runs. The other night I started it up, running extremely rich, with a miss I started doing chores and it cleared up and ran perfect. I got excited then it backfired through the exhaust and died. I got it to start back up, but rich and a miss again. ANY IDEAS?? I ve been working on tractors forever but this one has blown my mind